1. Field of the Invention
This invention relates to a die cutter, and more particularly a rotary cutting machine and tool for production of all kinds of die cut labels.
2. Description of the Prior Art
The increasing use of computers for accounting and other repetetive operations has led to a corresponding increase in the employment of the computer print-out to print a label which is used for dispatch of an account or other material. The labels used are generally self-adhesive labels and they are presented to the computer print-out arranged on a continuous backing sheet in parallel rows. Not only in the field of computer labels can this system be used; it is flexible and can also be used to produce labels for automatic application onto any product from reels or sheets for the packaging industry, or any use as may be found for any label of any kind which is manufactured.
The production of such labels in the form aforesaid has hitherto been effected either by a discontinuous stamping operation which is very slow, or by a rotary die cutting machine in which a laminate comprising a self-adhesive material on a backing is led under a solid shaft having cutters thereon which cut through the self-adhesive material around predetermined areas defining the labels, but do not cut through the backing. The surplus self-adhesive material is then removed, leaving the backing with a succession of parallel transverse rows of labels.
Although the rotary cutting machine just described is considerably faster than stamping, it nevertheless has considerable disadvantages. There is no standardisation in computer print-out labels or the spacing between labels. If, therefore, the size of the label is to be changed or the spacing between the labels altered, then a different die cutter is required. These die cutters are very expensive, and a heavy capital investment is required if even a modest range of label sizes and spacings is to be produced.
A different, but equally serious disadvantage stems from the very precise depth of cutting that the device must provide. If the cut is not deep enough, then separate self-adhesive labels will not be formed. But if the cutter penetrates too far into the laminate, the entire laminate will be severed and it will not then be suitable for a computer print-out or any present labelling product. Due to the engraved outside diameter of the cutter, the cutter shaft can only be held at the ends thereof and there is consequently a slight bowing of the cutter shaft in its central region. In order to compensate for that bowing, the cutter shaft must be non-uniform, in that it must have a larger cross-section near the centre than at the ends. All this makes the cutter shaft very expensive and unstable, as it spins, because it is unsupportable. It becomes highly susceptible to speed and thrust, and consequently its accuracy and quality of production can be affected especially as it becomes older and more used.